1. Field of the Invention
This invention relates to a transmission chain for a conical disk transmission comprising a plurality of intercoupled links each receiving two hinge pins which are situated transversely to the link plane and extend through link apertures, and whose end surfaces co-operate, as frictional surfaces, with the conical surfaces, and whose longitudinal sides form surfaces for rolling contact, having a radius of curvature differing from that of the co-operating rolling-contact surface.
2. Description of the Prior Art
This transmission chain, which is already a considerable improvement with respect to the prior art as disclosed in applicants' U.S. Pat. No. 4,337,057, issued June 29, 1982 and assigned to the present assignee, is particularly suited for higher powers up to e.g. a thousand kW and more. Although of course when used for smaller powers the efficiency of the transmission is an important factor, this efficiency gains in importance when greater powers have to be transmitted, as every improvement of the efficiency, however small it may be, leads to a significant reduction of the heat generated in the transmission. So if, e.g., a power of about 2000 kW must be transmitted, an improvement of the efficiency of 0.5% results in a decrease of the heat generated of 10 kW.
A first factor which results in losses is the movement of the pins with respect to the surface of the link openings with which they co-operate. Such a movement occurs when the links enter between the conical disks, and when they leave them. It would be desirable to have a pure rolling movement of the co-operating surfaces of pins and links with respect to each other; only then would very little heat be generated. When, however, the pins slide with respect to the surfaces of the links, friction losses occur which result in a decrease of efficiency and consequently the generation of heat. The nature of a rolling movement of a first curved body over a lesser curved plain of a second body requires that in each of the final positions of the first body there must always be some space between the two bodies in the opposite other final position. In the transmission chain according to the abovementioned prior art this is not the case so that the co-operating surfaces of the two parts do not move in a purely rolling movement over each other but also slide with respect to each other; it is clear that such a sliding movement must be limited as much as possible.
The known transmission chain uses links of which the openings have straight boundaries; when the transitions between the edges of the openings have a small radius of curvature there are significant concentrations of mechanical stresses in these transitions which quickly lead to fatique cracks. Preferably the links and pins will have the configuration shown in FIG. 11 of the abovementioned U.S. Pat. No. 4,337,057, thus having transitions and rounded parts with a large radius of curvature. However, this has as a result that the fixation of the position of the pins in a direction perpendicular to the direction of movement of the chain occurs in points which lie relatively far from the rolling surfaces of the link openings, which results in the fact that the play between the links and the pins, necessary for the rolling movement over each other, is increased and this again leads to an increase of the distance over which the parts can glide with respect to each other.